The present invention relates to ophthalmic devices. More particularly the invention is directed to composite ophthalmic devices.
The use of various ophthalmic devices, such as contact lenses and corneal implants, are known for the correction of vision abnormalities. Such ophthalmic devices typically are designed to correct one abnormality, e.g., myopia, and made from one optical polymeric material. There have been attempts to produce composite contact lenses having more than one polymeric material. Composite contact lenses having a relatively hard center section circumscribed by a soft and wettable edge section have been disclosed by various publications. The soft and wettable edge section of the lens is designed to provide improved comfort on the eye, thereby reducing the eye irritation often experienced by hard contact lens users. Additionally, there have been attempts to produce bifocal rigid contact lenses having two optical materials having different indices of refraction. Such attempts typically produce a composite lens by laminating or cementing two separately produced, e.g. lathe formed, component lenses. However, the cementing approach requires perfectly or near perfectly matching component lenses to produce the composite lens. In addition, the process for separately producing component lenses and the process for precisely cementing the component lenses are labor intensive and time consuming and are not conducive to mass producing bifocal lenses. Moreover, the cementing process is not highly suitable for producing hydrogel contact lenses since typical hydrogel contact lenses are formed in a dehydrated state and subsequently hydrated. When a hydrogel lens is hydrated, the lens swells and changes its dimension. Consequently, a composite hydrogel lens additionally experiences optical distortion and delamination problems.
There remains a need for composite lenses that can be produce with a production process that is simple and can easily be used to mass produce such lenses.